Get btrfs subvolume disk usage sorted by incremental size

btrfs-subvolume-usage.py

#!/usr/bin/env python3
# NOTE: btrfs quota must be enabled for this to work:
#           btrfs quota enable /btrfs/
import os
import sys

usage = {}
for line in os.popen('btrfs qgroup show / --raw', 'r'):
    # 0/10784   15678980096       557056
    if not line.startswith('0/'):
        continue

    p = line.strip().split()
    sid = p[0].split('/')[1]
    usage[sid] = (int(p[1]), int(p[2]))


output = []
for line in os.popen('btrfs subvolume list /', 'r'):
    # ID 10790 gen 301424 top level 264 path .snapshots/2878/snapshot
    if not line.startswith('ID'):
        continue

    p = line.strip().split()
    sid = p[1]
    assert p[7] == 'path', p
    path = p[8]

    u = usage[sid]
    output.append((sid, u[0], u[1], path))

output.sort(key=lambda x: x[2])
for o in output:
    print("{:6}  {:14,d}  {:14,d}  {}".format(*o))